Dive bombers to Ceylon 1942

[EwenS]

Approaching and leaving the launch-point. You want to minimize your exposure to hostile attack. Under hostile attack, of course you speed up, so far as you can.

In practice, still no. If you look at the various occasions when the USN carriers were used for raiding operations, as opposed to supporting amphibious landings, their tactics remained relatively unchanged from the earliest in the first few months of 1942 to later ones at the end of 1943. Those 1942 operations battleships were not along for the ride, the escorts being heavy cruisers and destroyers (and with a single 18 knot fleet oiler attached).

It was a case of topping off the fuel tanks, especially of escorting destroyers from the tankers or the larger vessels, on one day then leaving the oiler behind and making a 25 knot overnight dash to arrive at the launch position just before dawn. Then a day of strikes and retire under cover of darkness before the enemy could react.

So they were covering 250-300 miles on the run in. To do it faster meant burning much more fuel.

 

[WARSPITER]

Most WWII fleet type carriers could get to top speed from a start point of twenty knots in 1 to 2 minutes. Going to full speed wasn't
done unless absolutely necessary due to possible damage to parts of the drive system and possible damage to equipment or
injury to crew from increased instability.

Carriers were, as far as possible, made to turn well. Some were better than others and in the case of speed/turns the load being
carried and sea conditions played a big part.

Dive bombers weren't worried about a carrier doing an extra five or ten knots with turning and anti aircraft fire being the best defence
if the CAP was pierced.

 

[Thumpalumpacus]

In practice, still no. If you look at the various occasions when the USN carriers were used for raiding operations, as opposed to supporting amphibious landings, their tactics remained relatively unchanged from the earliest in the first few months of 1942 to later ones at the end of 1943. Those 1942 operations battleships were not along for the ride, the escorts being heavy cruisers and destroyers (and with a single 18 knot fleet oiler attached).

It was a case of topping off the fuel tanks, especially of escorting destroyers from the tankers or the larger vessels, on one day then leaving the oiler behind and making a 25 knot overnight dash to arrive at the launch position just before dawn. Then a day of strikes and retire under cover of darkness before the enemy could react.

So they were covering 250-300 miles on the run in. To do it faster meant burning much more fuel.

Saratoga and Princeton, pulling about 30 kts on the run-in to Rabaul in Nov 43. Almost 500 miles.

 

[Steamed_Banana]

In windless conditions to launch a deck load strike. The IJN never used flight deck catapults on their carriers, so high speed was specified to aid in carrier ops, as was the need for light weight aircraft.

The speed chosen when under attack had to also factor in the ability of screening ships to provide AA protection ( however circular AA formations were not used in the KB even at Midway) and the best speed for manoeuvre which wasn't necessarily maximum speed.

Ok but you all I'm sure have read some of the battle histories, the IJN carriers in particular, but US carriers too, seemed to twist and turn at flank speed to avoid bombers, often successfully.

Anyway, the whole debate is a bit of a derail. For Ceylon let's say 25 knots I'm fine with that

 

[RCAFson]

Most WWII fleet type carriers could get to top speed from a start point of twenty knots in 1 to 2 minutes. Going to full speed wasn't
done unless absolutely necessary due to possible damage to parts of the drive system and possible damage to equipment or
injury to crew from increased instability.

Carriers were, as far as possible, made to turn well. Some were better than others and in the case of speed/turns the load being
carried and sea conditions played a big part.

Dive bombers weren't worried about a carrier doing an extra five or ten knots with turning and anti aircraft fire being the best defence
if the CAP was pierced.

That's very unlikely. See here for actual data:

H.M.S. Hood Association-Battle Cruiser Hood - Ship Specifications and Armament: Performance & Seakeeping

www.hmshood.org.uk

(note the reduction of speed in tight turns!)

There's a finite amount of power that can be applied to the prop shafts before the props begin to cavitate and the turbine blades can be stripped if too much steam is applied when the turbines are moving slowly and then there's the sheer inertia of the ship.

 

[buffnut453]

The AVG was 100% a tool / proxy of the US, it may not have been USAAF but it was certainly made up of US military personnel given special dispensation to take on the mission, and was operating at the sufferance (and with the robust support) of the US government.

Sorry for not keeping up with this thread...we're moving house so I'm a tad distracted.

However, had to jump in on this comment. The AVG had its genesis in the League of Nations concept for an "International Air Force" that would be formed from wealthy nations to defend weaker nations against aggression.

In parallel to efforts in the US, the UK was also establishing a volunteer force, with plans well advanced in Nov 1941 to send one squadron each of Buffalos and Blenheims to operate under Chennault's command (a BVG, if you like). Airframes were being pulled from front-line squadrons and the British government had already secured approval from New Zealand and Australia to approach personnel from those nations to fill the required number of volunteers.

I struggle with the idea that the US government provided robust support to the AVG. Washington did its best to disown the AVG, indeed there were zero protections, diplomatic or otherwise, if any AVG personnel were to be killed or captured.

When we factor in the above considerations, and note that the AVG's airframes were gifted by the UK, and the aircraft were erected at RAF Mingaladon, this clearly wasn't just a US show.

I'll no jump off the "thread drift" train and try to digest the many posts since I last read the thread. Hopefully, I'll have more on-topic comments shortly.

 

[Thumpalumpacus]

[...] ...we're moving house so I'm a tad distracted.

You have my sympathies, brotha. I'd rather have a couple of teeth pulled.

 

[EwenS]

If you look at many of the diagrams in "Shattered Sword" which look at the whole picture of the KB at Midway at various points during the day, rather than a photograph of a single isolated carrier, it is striking to note that the initial movement with regard to a single attack is for the whole fleet to make a similar turn in the same direction. However as the attack develops individual ships may have to continue a turn or reverse a turn according to its own individual circumstances. The result seems to be that it becomes even further spread out than normal with individual ships unable to support each other.

I came across this document, a product of someone's research using Japanese records showing their carrier formations at various times in 1942. There is one given for Operation C noted as a "cruising formation", which is evidenced by some photos.

https://dreadnoughtproject.org/friends/dickson/IJN%201942%20Carrier%20Formations.pdf

Kido Butai in the Indian Ocean – 1942 Part I - War History

Akagi leaving Celebes Island for the attack on Colombo, 26 March 1942. In the background are other carriers and battleships of the carrier striking force.

warhistory.org

Kido Butai in the Indian Ocean – 1942 Part II - War History

The Japanese strike force advancing to the Indian Ocean. Ships shown from left to right are: Akagi, Soryu, Hiryu, Hiei, Kirishima, Haruna, and Kongo.

warhistory.org

However these relate to the early part of the Operation where the KB was leaving Staring Bay, Celebes (at 0700 26th March at 12 knots) and then heading south to negotiate Ombai Strait between the Lesser Sunda Islands and Timor. Captions on others taken at this time refer to the ships being "on the route to the Indian Ocean".

On the day of departure Soryu deployed 5 pairs of Kate TB in succession to scout the route to Ombai Strait and another 16 Vals and 4 Kates in 5 consecutive AS patrols. The next day it was Hiryu's turn with 5 Kate pairs in succession to scout the route and 17 Vals and 3 Kates on consecutive AS patrols.

See "The Darkest Hour Vol 1" by Michal A. Piegzik. This author has researched his books in Japan using Japanese records. I'm still on Vol 2 but haven't come across any further details of KB formations.

These seem to be tricky waters to negotiate with the Strait narrowing to about 26km. If it is anything like some of the other straits leading out through the Outer Malay Barrier to the IO, currents could be strong flowing out into the IO. Given the deployment of scouts on those two days would suggest that the Japanese were not entirely sure of what lay ahead of them from their charts.

The KB then turned south west to enter the IO. It was south of Bali by the 28th at which point it turned West before turning north west to head for Ceylon.

A few years back ISTR an internet debate about exactly what formation the KB used in the IO. I certainly wasn't aware at that time of the route they used to enter the IO and I'm not sure how many participants were. But it now seems to me that the formation chosen in those early stages makes sense in potentially restricted waters, with an arc of destroyers up front for AS cover and the main body in line with searoom to avoid any navigational hazards that might be encountered.

The unanswered question then and now is did they then revert to a more box like formation as used at PH & Midway once open ocean was reached. My guess would be that they did.

It is worthy of note however just how spread out these KB formations were and how few escorts there were to cover that large amount of ocean in between. That makes it difficult for one ship to support another when under air attack. It does however give each carrier a large amount of free airspace around it to launch, assemble and land its aircraft from. This was one of the things the IJN changed in 1944.

By the way, in June 1944 at Philippine Sea Taiho was recorded as travelling at 26 knots when torpedoed iimmediately following the launch of her big strike. (By implication so were Shokaku & Zuikaku in her group). She was able to maintain that speed after being torpedoed. She was still running at over 20 knots when the fatal internal explosion occurred some six and a half hours later.

 

[SaparotRob]

That's very unlikely. See here for actual data:

H.M.S. Hood Association-Battle Cruiser Hood - Ship Specifications and Armament: Performance & Seakeeping

www.hmshood.org.uk

(note the reduction of speed in tight turns!)

There's a finite amount of power that can be applied to the prop shafts before the props begin to cavitate and the turbine blades can be stripped if too much steam is applied when the turbines are moving slowly and then there's the sheer inertia of the ship.

I always wondered about that. When I watch an action packed adventure and our heroes reverse engines, I think about all the external and internal forces being applied against all those hundreds of smaller components dealing with massive forces. Inertia is a bitch.

 

[SaparotRob]

You have my sympathies, brotha. I'd rather have a couple of teeth pulled.

I'm old. I'm running out of teeth.

 

[EwenS]

I always wondered about that. When I watch an action packed adventure and our heroes reverse engines, I think about all the external and internal forces being applied against all those hundreds of smaller components dealing with massive forces. Inertia is a bitch.

You only need to look at PoW in Dec 1941 when that first torpedo hit removing the propellor and aftmost shaft section to realise the forces involved. When it was restarted the flailing end gradually destoyed all the bulkheads down the shaft alley as the various shaft sections came apart.

 

[SaparotRob]

You only need to look at PoW in Dec 1941 when that first torpedo hit removing the propellor and aftmost shaft section to realise the forces involved. When it was restarted the flailing end gradually destoyed all the bulkheads down the shaft alley as the various shaft sections came apart.

You're right. I forgot about that.

 

[Steamed_Banana]

If you look at many of the diagrams in "Shattered Sword" which look at the whole picture of the KB at Midway at various points during the day, rather than a photograph of a single isolated carrier, it is striking to note that the initial movement with regard to a single attack is for the whole fleet to make a similar turn in the same direction. However as the attack develops individual ships may have to continue a turn or reverse a turn according to its own individual circumstances. The result seems to be that it becomes even further spread out than normal with individual ships unable to support each other.

I came across this document, a product of someone's research using Japanese records showing their carrier formations at various times in 1942. There is one given for Operation C noted as a "cruising formation", which is evidenced by some photos.

https://dreadnoughtproject.org/friends/dickson/IJN%201942%20Carrier%20Formations.pdf

Kido Butai in the Indian Ocean – 1942 Part I - War History

Akagi leaving Celebes Island for the attack on Colombo, 26 March 1942. In the background are other carriers and battleships of the carrier striking force.

warhistory.org

Kido Butai in the Indian Ocean – 1942 Part II - War History

The Japanese strike force advancing to the Indian Ocean. Ships shown from left to right are: Akagi, Soryu, Hiryu, Hiei, Kirishima, Haruna, and Kongo.

warhistory.org

However these relate to the early part of the Operation where the KB was leaving Staring Bay, Celebes (at 0700 26th March at 12 knots) and then heading south to negotiate Ombai Strait between the Lesser Sunda Islands and Timor. Captions on others taken at this time refer to the ships being "on the route to the Indian Ocean".

On the day of departure Soryu deployed 5 pairs of Kate TB in succession to scout the route to Ombai Strait and another 16 Vals and 4 Kates in 5 consecutive AS patrols. The next day it was Hiryu's turn with 5 Kate pairs in succession to scout the route and 17 Vals and 3 Kates on consecutive AS patrols.

See "The Darkest Hour Vol 1" by Michal A. Piegzik. This author has researched his books in Japan using Japanese records. I'm still on Vol 2 but haven't come across any further details of KB formations.

These seem to be tricky waters to negotiate with the Strait narrowing to about 26km. If it is anything like some of the other straits leading out through the Outer Malay Barrier to the IO, currents could be strong flowing out into the IO. Given the deployment of scouts on those two days would suggest that the Japanese were not entirely sure of what lay ahead of them from their charts.

The KB then turned south west to enter the IO. It was south of Bali by the 28th at which point it turned West before turning north west to head for Ceylon.

A few years back ISTR an internet debate about exactly what formation the KB used in the IO. I certainly wasn't aware at that time of the route they used to enter the IO and I'm not sure how many participants were. But it now seems to me that the formation chosen in those early stages makes sense in potentially restricted waters, with an arc of destroyers up front for AS cover and the main body in line with searoom to avoid any navigational hazards that might be encountered.

The unanswered question then and now is did they then revert to a more box like formation as used at PH & Midway once open ocean was reached. My guess would be that they did.

It is worthy of note however just how spread out these KB formations were and how few escorts there were to cover that large amount of ocean in between. That makes it difficult for one ship to support another when under air attack. It does however give each carrier a large amount of free airspace around it to launch, assemble and land its aircraft from. This was one of the things the IJN changed in 1944.

By the way, in June 1944 at Philippine Sea Taiho was recorded as travelling at 26 knots when torpedoed iimmediately following the launch of her big strike. (By implication so were Shokaku & Zuikaku in her group). She was able to maintain that speed after being torpedoed. She was still running at over 20 knots when the fatal internal explosion occurred some six and a half hours later.

I didn't realize Piegzik did a series on this, I liked his one on the Aleutian campaign quite a bit. I'll have to get a copy.

 

[RCAFson]

FAA and RAF divebombing- trial data from Smith's 'Dive Bomber!'

Swordfish:

The Swordfish could also be used as a dive-bomber. During 1939, Swordfish on board HMS Glorious participated in a series of dive-bombing trials, during which 439 practice bombs were dropped at dive angles of 60, 67 and 70 degrees, against the target ship HMS Centurion. Tests against a stationary target showed an average error of 49 yd (45 m) from a release height of 1,300 ft (400 m) and a dive angle of 70 degrees; tests against a manoeuvring target showed an average error of 44 yd (40 m) from a drop height of 1,800 ft (550 m) and a dive angle of 60 degrees. (wikipedia entry sourced to Smith. page 66, and is a fairly accurate summary)

Although Centurion was not a fast ship, it's interesting to note that accuracy against a manoeuvring ship went up.

RAF and the Fairey Battle:

...Training Command for example did not seem to share the view that dive
bombing was either no longer relevant or that the problems could not be
overcome. After first repeating yet again that: 'No instructions explaining the
theory and principles [of dive bombing] have ever been circulated . . .', they
reiterated that a compromise might still be possible. For example modern
aircraft like the Battle they felt *. . . can dive successfully at an angle up to
approximately 60°, it is very strongly suggested that the AGA dive bomb sight
referred to by Sqdn Ldr C.D. Adams in his report on his attachment to the
Swedish Air Force this year should be purchased and suitable tests made
immediately." They supplied figures to support their case, although the angles
used hardly justified the term dive bombing.
The subject was returned to on 20 October when it was stated that although
the Air Ministry thought dive bombing was obsolete not everyone shared that
opinion in the RAF. It was suggested that the officials might not be aware of the
capabilities and possibilities of dive bombing: 'it may not be realised that Battle
aircraft can dive at 60° without difficulty and within the limitations laid down. It
will be seen, therefore, that if the Swedish sight was obtained and the dive bomb
reports of No 15 (Bomber) squadron circulated that we should have very
accurate bombing on this type of aircraft in a reasonably short time... ."
Further backing was given in a memo of November 1938. The points made
were that shallow dive bombing was valueless, despite the RAF's concentration
exclusively on that type, and the angle of dive to be efficient had to be at least 45°.
The overwhelming advantages of steep dive bombing from 6,000ft were
considered to be so great as to justify its retention, if a suitable aircraft could be
obtained. Finally if it was shown that even the Battles could be dived steeply then
all Battle squadrons should be trained in this technique..." (page 56)

In fact 6 Battle squadrons conducted high angle dive-bombing trials, according to Smith and achieved reasonable accuracy (130yd CEP) but I suspect the pull out height was on the order of 3000ft. Apparently, the idea was for the Battle to approach at 12K ft, then a shallow dive to 6k ft then a steep dive to release altitude.

 

[WARSPITER]

That's very unlikely. See here for actual data:

H.M.S. Hood Association-Battle Cruiser Hood - Ship Specifications and Armament: Performance & Seakeeping

www.hmshood.org.uk

(note the reduction of speed in tight turns!)

There's a finite amount of power that can be applied to the prop shafts before the props begin to cavitate and the turbine blades can be stripped if too much steam is applied when the turbines are moving slowly and then there's the sheer inertia of the ship.

Aircraft carriers were a different design and type to battle cruisers and battle ships. Carriers were made to turn at high speed on a larger radius
in order to quickly get into position to launch the main weapons (aircraft).

Battleships were made to turn on a shorter but slower radius to get into position to fire the main weapons.

With this in mind carriers did not lose anywhere the speed that a battleship does when turning to action.

Couple this with the weight of the two types and at times the power available and there is a big difference in tactical use.
Hood had 144,000 shp and a weight of 47,000 tons compared to the later Essex carrier with 150,000 shp and a weight with full load of 37,000 tons.

Either way, in a "close combat" situation against dive bombers speed wasn't a major consideration.

 

[Steamed_Banana]

Bert Horden, in his wartime memoir, "Shark Squadron Pilot", gives a fairly detailed account of dive bombing in a Kittyhawk on pages 51-52.

"Dive-bombing was from about 6,000-8,000 ft down to 1,000 ft (1828-2438m down to 304 m). The target was approached until it disappeared under the center of the port wing, count to three and then go into a dive down to the left until the target was in front of the aircraft nose. At about 2,000 ft (609 m) pull up, count on, two and then release the bomb or bombs. Then we were to reform at about 5,000 ft (1524 m) in the same formation back to base. The dive was at about sixty degrees but it felt like ninety!"

So 60 degree dive with a 5-7,000 ft drop, means I think a pretty high speed dive.

This was in early 1943